Copper chromium oxide catalyst

This catalyst is pr ared by the decomposition of basic copper ammonium chromate the main reactions may be written as  

Hydrogenations with coppcr-chromium oxide catalyst are usually carried out in the liquid phase in stiiiniess steel autoclaves at pressures up to 5000-6000 lb. per square inch. A solvent is not usually necessary for hydrogenation of an ester at 250° since the original ester and the alcohol or glycol produced serve as the reaction medium. However, when dealing with small quantities and also at temxieratures below 200° a solvent is desirable this may be methyl alcohol, ethyl alcohol, dioxan or methyh c/ohexane. 

The catalyst, which may be regarded as complementary to Raney nickel (Section VI,5) is largely used for the hydrogenation of esters (esters of memo-basic and of dibasic acids to alcohols and glycols respectively)  

The catal3rst is inactive for the hydrogenation of the (isolated) benzene nucleus and so may be used for the hydrogenation of aromatic compounds containing aldehyde, keto, carbalkoxy or amide groups to the corresponding alcohols, amines, etc., e.g., ethyl benzoate to benzyl alcohol methyl p-toluate to p-methylbenzyl alcohol ethyl cinnamate to 3-phenyl-l-propanol. 

Dissolve 15 5 g. of A.R. barium nitrate and 130 g. of A.R. cupric nitrate trihydrate in 450 ml. of water at SO. Prepare a solution of sodium chromate by dissolving 89 g. of recrystallised sodium dichromate dihydrate in 200 ml. of water and adding 112 5 ml. of cone, anunonia solution (sp. gr. 0 90). Add the warm solution (80°) of nitrates in a thin stream, with stirring, to the sodium chromate solution (at 25°). Collect the orange precipitate by suction filtration, wash it with two 50 ml. portions of A ter, drain well, and dry at 76-80° for 12 hours powder finely. 

2Cu(N03)2 + Na2Cr207 + 4NH3 + 3H20 - 2CuNH4(OH)CrO + 2NaNOs + 2NH4N03 

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By passing the alcohol vapour over a copper - chromium oxide catalyst deposit on pumice and heated to 330°, for example ... 

This preparation illustrates the use of the copper-chromium oxide catalyst in the r uotion of esters of dibasic acids to glycols ... 

Some more recent processes have been developed which involve direct hydrogenation of the oil to the fatty acid and 1,2-propane diol. These high-temperature (>230 °C) and high-pressure processes generally use a copper chromium oxide catalyst. 

Naturally occurring fatty alcohols used in the fragrance industry are produced principally by reduction of the methyl esters of the corresponding carboxylic acids, which are obtained by transesterification of natural fats and oils with methanol. Industrial reduction processes include catalytic hydrogenation in the presence of copper-chromium oxide catalysts (Adkins catalysts) and reduction with sodium (Bouveault—Blanc reduction). Unsaturated alcohols can also be prepared by the latter method. Numerous alcohols used in flavor compositions are, meantime, produced by biotechnological processes [11]. Alcohols are starting materials for aldehydes and esters. 

Synthesis from Geraniol or Nerol. ( )-Citronellal can be obtained by vapor-phase rearrangement of geraniol or nerol in the presence of, e.g., a barium-containing copper-chromium oxide catalyst [63]. 

Dihydrophenanthrene has been prepared from 2,2 -bis(bromomethyl)biphenyl and sodium 8 from the reduction of 2,2 -diiodobibenzy 1 in the presence of 1% palladium on barium carbonate catalyst 8 by the hydrogenation of phenanthrene in the presence of nickel8 or copper-chromium oxide catalyst 10 and by the coupling of 2,2 -bis(bromomethyl)biphenyl with lithium phenyl.11... 

It diiiers from the copper. chromium oxide catalyst described in Section VI,6 in that it has not been extracted with 10 per cent, acetic acid—a process which presumably removes some copper oxide. 

Continuous steam distillation, 147, 148 Cooling baths, 61 Cooling curve method, 26 Copper bronze, activated, 193 Copper - chromium oxide catalyst, for aldehyde synthesis, 318, 321 for hydrogenation, 872, 873 hydrogenolysis with, 872J Copper phthalocyanine, 983 Copper powder, 192 Copper sulphate, as desiccant, 40, 41 Cork stoppers, 55 boring of, 56... 

COPPER-CHROMIUM OXIDE CATALYST ( COPPER CHROMITE CATALYST)... 

Aldehydes are readily hydrogenated to the corresponding alcohols over nickel and copper-chromium oxide catalysts.1 In general, Raney Ni, especially highly active ones such as W-6,2 are preferred to other nickel catalysts for the hydrogenations at low temperatures and pressures. Raney Ni may further be promoted by the addition of triethylamine2 or triethylamine and a small amount of chloroplatinic acid,3 4 as shown in eqs. 5.1 and 5.2. 

Copper-chromium oxide catalyst is effective for the hydrogenation of aldehydes at a temperature of 125-150°C.1 The hydrogenation of benzaldehyde over copper-chromium gives a high yield of benzyl alcohol even at 180°C without hydrogenolysis to give toluene (eq. 5.5).7... 

The hydrogenation of fatty acids or fatty esters is of industrial importance for the production of fatty alcohols. Usually, the hydrogenation is performed in slurry-phase or fixed-bed reactors over copper-chromium oxide catalyst at elevated temperature and pressure.37 Rieke et al. investigated the hydrogenation of methyl dodecanoate over copper-chromium oxide at 280°C and 13.8 MPa H2, in order to study the side reactions that occur during hydrogenation.37 On the basis of the potential reaction routes described by Rieke et al., the pathways leading to C12 alcohol and various byproducts are summarized in Scheme 10.2, with exclusion of the formation and reactions of acetals. It has been found that both catalytic activity and selectivity correlated well with the crystallinity of the copper-chromium ox-... 

Catalytic hydrogenation of alkyl aryl ketones and diaryl ketones to hydrocarbons is most convenient provided that high-pressure apparatus is available. Coppoalumina and copper-chromium oxide catalysts have been used. At 100-130° alcohols are formed, but at 180-250° excellent yields of the corresponding hydrocarbons are obtained. ... 

Catalytic hydrogenation of amides to amines requires drastic conditions in general, a temperature of 250 to 265" and a pressure of 200 to 300 atm. over copper-chromium oxide catalyst using dioxane as the solvent. The yields of primary amines from unsubstituted amides are lowered mainly by the formation of secondary amines, viz.,... 

The keto group of a keto ester may be preferentially reduced by catalytic hydrogenation. Excellent yields of hydroxy esters are obtained. Copper-chromium oxide catalyst has been employed in the preparation of methyl p-(a-hydroxyethyl)-benzoate and several aliphatic -hydroxy esters. The last compounds have also been made by hydrogenation over nickel catalysts.Substituted mandelic esters are prepared by catalytic reduction of aromatic a-keto esters over a palladium catalyst. Similarly, platinum oxide and copper-chromium oxide have been used in the aliphatic series for the preparation of the a-hydroxy diester, diethyl... 

Decarboxylation can be achieved by heating the acids above their melting points, often in the presence of a copper-chromium oxide catalyst, and it is possible to remove one group at a time from imidazole-4,5-dicarboxylic acid by heating the monoanilide. Studies of the kinetics of decarboxylation of 5-aminoimidazole-4-carboxylic acids implicate a first-order decarboxylation of both the acid and the zwitterion the anion is stable and not... 

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